He was kicked in the head by a much bigger 15 year old. It is dangerous and irresponsible to let large teenagers on bouncy castles with smaller children.
It is very, very sad that it came to a court case, but the boy's brain damage is so bad, he will need constant care for the rest of his life.
Bouncy castles are fun for small, light children, carefully supervised, but, as the mother of 2 large teenaged boys, I would never hire one for teenagers.